1. Field of the Invention
The present invention relates to a method of manufacturing a liquid ejection head.
2. Description of the Related Art
Known liquid ejection heads for ejecting liquid include ink jet recording heads to be used for ink jet recording systems. Ink jet recording heads generally include one or more ink channels, ejection energy generating elements arranged at a part of the ink channel or each of the ink channels to generate energy for ejecting ink and minute ink ejection ports for ejecting ink.
For example, a method as described below is known for manufacturing such an ink jet recording head. Firstly, a mold of an ink channel is formed on a substrate, which contains heater elements formed therein in advance, by means of a photosensitive material and then a coating resin layer that becomes a channel forming member is formed to coat the channel mold. Thereafter, ejection ports are formed in the coating resin layer. Then, a manufactured ink jet recording head comes out as the photosensitive material that has been used for the mold is removed. With this manufacturing method, flow channels, ejection ports and so on can be formed by way of high precision micro processing steps because a photolithography technique that is being used in the field of semiconductors is also employed for the method. This manufacturing method involves exposure to light by a semiconductor exposure apparatus that operates as means for setting a photosensitive resin material. The photosensitive resin material is exposed to light by way of a reticle having a desired profile and by means of a semiconductor exposure apparatus. The part of the photosensitive resin material that is shaded and hence not exposed to light remains unset and is removed in a subsequent removal step.
In recent years, there is a tendency of using long chips in order to realize high-speed printing. There is also a tendency of exposing collectively a plurality of chips to light from the viewpoint of reducing the time required for the exposure step. For these reasons, a pattern is arranged nearly to the limits of the angle of view of the reticle to be used for the exposure step. If such is the case, the rays of light that are transmitted through a portion of the projection lens system representing a large curvature in a semiconductor exposure apparatus are affected by the aberrations of the lens to by turn adversely affect the profiles of the ejection ports. Such a phenomenon occurs because, when the rays of light coming from the exposure apparatus are so adjusted that the pattern formed at and near the center of the reticle may be accurately projected on the resist, the rays of light irradiated from the semiconductor exposure apparatus are refracted to inward directions of the lens in regions remote from the center of the reticle. Differently stated, there arise instances where a pattern is formed at and near the limits of the angle of view of the reticle for stepper exposure and the ejection ports 6 that correspond to the parts exposed to the rays of light that have passed at and near the limits of the angle of view represent an outwardly inclined profile (see FIG. 10).
In view of the above-identified problem, Japanese Patent Application Laid-Open No. 2001-264637 disclosed means for correcting the aberrations of the lens of a lens system. The means lies in an ingeniously devised lens system. With such a means, a spherical aberration correcting optical system is mounted in the inside and the spherical aberration is corrected by moving the movable lens group of the system in the directions of the optical axis.